In a drug delivery device, a piston within a cartridge that contains drug may be displaced with respect to the cartridge in the distal direction by a piston rod which moves in the distal direction with respect to the cartridge. In order to provide for a reusable device, after the cartridge containing the drug has been emptied, the piston rod often has to be moved back from a distal end position to a proximal starting position. Thereby, a dose of drug can be expelled from the cartridge. WO 2009/049885 A1 describes an injection device which can be reset by removing the cartridge and thus disengaging the toothings of a steering element and a cylindrical sleeve, so that the piston rod can freely rotate.